No repeating the same workouts are not less effective as long as you continue to target the areas you want to work on. Don’t leave any part of these 4 things out because you could be missing some results.
Instead of trying to increase reps of your workouts, you should try to increase weight. If you want to continue to get stronger and more fit adding more weight helps. Even on bodyweight core you can add a medicine ball into your workout. If you are content with the look of your body staying at a consistent weight and schedule will keep you in the same shape.
It is advised you do cardio 3-5 days a week at 20-30 minute intervals.
Meal prepping is a way to keep you on a consistent and healthy diet. It saves you more time, you have well balanced meals already prepared, and you can avoid the temptation of eating out when you stuck on what to eat.